off idle stumble/hesitation (BOMBED or stock)

[rbattelle]

Kind of sounds like those set of clattering teeth one can buy at a joke shop.

Yup, that's what mine sounds like. I guess I can expect a CP-3 replacement in my future. Swell.



Except mine doesn't do it continuously. It'll click once, then be silent for a second or 2, then click again, then silence, then click again. It stops after about 6 clicks. And I can only hear it if I've got the windows down and I'm parked next to something that reflects the sound.



-Ryan

 

[rbattelle]

JStieger, I just thought of something.



Dodge apparently won't sell just the fuel control actuator... what about Cummins? And if you need a new CP-3 altogether, you might call them. If history is any indicator, they may be significantly cheaper than Dodge.



If all else fails, call Scheid and see if they can rebuild the CP-3 yet (I talked with them a couple months ago and they said they couldn't, but things might have changed).



If Scheid can't do it, there's got to be some Bosch authorized service center somewhere in North America that can do it. How do we find it, though?



On Edit:

I checked the Dodge parts manual and they list the CP-3 as a single unit. The FCA isn't even labeled and has no part number associated with it. BTW, P/N for the CP-3 is 4429 689 (that's Dodge's part number, not Cummins). I'm not even sure how that FCA attaches to the backside of the CP-3... I've never noticed any screws or anything back there.



On Edit 2:

Here's a link to find Bosch diesel service centers. Each center has a field labeled "Factory Trained For: "... now we just need to decipher the symbols to determine how to find a shop that can rebuild a CP-3... maybe "CR" means "Common Rail"?



On Edit 3:

Oo. Oo. Oo. CR MEANS DODGE DIESEL COMMON RAIL ENGINES!!!!!!!!



WOO HOO!! WE'RE NO LONGER CHAINED TO DODGE! Here's a link that explains the coding:

CR = Dodge pickup with Cummins engine and electronically

controlled high-pressure common rail system

I could not possibly be any happier about this. Oo. Oo. Oo.



-Ryan

 

[JStieger]

Mine is pretty loud - I can hear it over the radio on a low volume and slow acceleration with the windows up or down. The service manual stated that it will make an audible noise at startup, but this loud clicking noise is something that I have never heard before and it is just happening more and more frequently over the past week.



I recently ordered a Fluke 189 meter to replace my POS Walmart special and found out from a search that it can also be used to check my fuel rail sender voltage to see what my low end rail pressure was doing during this clicking, but the meter is on backorder for another month. I also ordered up a Cummins HPCR training and diagnostic manual from Tech Authority for reference and that's on backorder too! From what I researched the idle pressure is anywhere from ~4200 psi to 5xxx psi so my theory is that the sensor voltage would be fluctuating out of this range (probably lower) when the solenoid is acting up - unfortunately I have no way of checking this theory yet until I get to Industrial Injection and hook up their DRB3 tool. Also, thinking that their would be so much noise in the readings that perhaps a "low pressure number" would be hard to detect anyway as my truck is still very much driveable above ~1200 rpms.

 

[rbattelle]

Okay, I also checked my 2003 service manual, and there IS a procedure to remove the FCA. JSteiger, I strongly encourage you to do the procedure before throwing money at the problem! Upon removal you should be able to clean it. Step 5 of the removal process says:

Shake the FCA and listen for a rattle. If the FCA does not rattle, replace it.

If you (or anyone else reading this) wants a copy of that page of the manual, PM me and I'll email it to you...



-Ryan

 

[Big_H316]

Wjen I had to replace the cp-3 the local cummins shop could get me a new one for $1400 but they were on back order (go figure). The local Dodge house had a re-man unit for $900 but I had to turn in my old unit before STAR would let them release the re-man to me, what kind of crap is that. They then turned right around and said "you can buy it outright for $1750. " I looked at that guy and said "I'll be back in a couple of hours with the old one. " I've had zero problems with the re-man unit so far. And it has a one year warranty on it.

 

[rbattelle]

The local Dodge house had a re-man unit for $900

I wonder how much it would have been if you had eliminated the Dodge middle-man and went straight to the rebuilder...



-Ryan

 

[JStieger]

Update...

I just got back from Industrial Injection in SLC and we are stumped! Here's what happened in chronological order.



First, the tech hooked up the DRB3 to clear all the codes I generated when unplugging sensors while the engine was running. These codes did not come back, nor did any new ones.



Next, he ran the injector kill test and the rpms dropped like they should equally as each injector was shut off. He repeated the kill test again for verification.



Then we monitored the rail pressure and it was pretty much dead on 5300 psi setpoint and actual. Playing with the throttle from idle rpm up showed that the actual rail pressure followed the rail pressure setpoint fairly closely with no big variances suggesting that the CP3 / FCA / rail pressure relief valve were good.



Next we went for a 30 minute drive and I duplicated the issue numerous times. He monitored all sensors, including cam and crank (crank especially for injection timing) as well as the rail pressure and any codes and everything checked fine! Actual rail pressure was close to setpoint the whole time with no wild variances suggesting that the FCA was the culprit, the crank and cam sensors had the appropriate "square curve" happening on the graph, and no codes - nada injection misfire - nothing! Again, this strongly suggested all sensors were good as well as the CP3. Weird juju going on with no "smoking gun".



So we pulled back into the shop and discussed what could be happening. He said that he had looked at about 30 - 3rd gens with a similar sort of problem as mine and 10 of them had to have their ECMs reflashed or replaced due to all the chips/boxes they have been running (note I had run the BDDL programmer before). So before he could diagnose further he wanted the ECM eliminated from the picture. A quick phone call to Hinckley Dodge and I was getting my ECM reflashed 15 minutes later. The dealer tech commented that my idle felt rough seat-of-pants and I responded that was something we were trying to diagnose yet the dash tach or DRB tach doesn't show an idle variation.



After the reflash and with fingers crossed I leave the dealership and feather the throttle from idle to ~1700 rpms and... "poof-sputter-poof-clickity clack" and then takes off fine! Crap...



So I went back to Industrial Injection and talked to the tech again and he came up with some possibilities:



1) sticking injector that's not firing or is firing, but may be carboned up.

2) cracked nozzle (one of the heavily modded 3rd gens mentioned above had this problem as well as the bad ECM)

3) poor wiring connection somewhere

4) Air in fuel (can lead to retarded injection according to my Tech Authority Cummins HPCR class book)

5) broken valve springs that's not letting the compression build

6) dropped valve seat or loose valve seat (history of this on 2003's according to tech)



We agreed that 5) and 6) might be farfetched since the issue is only happening at a certain rpm. That is, if it was a mechanical issue, then my engine would be making noise all the time and/or oil pressure would go bad and/or fuel in oil and/or siezed engine???



Anyhow, I got an appointment set up for next Thursday and they will pull all my injectors and go through them. When my truck cools down, I will pull the valve cover and check my injector electrical connections and check for unusual valve movement or broken springs. I will also check the CP3 fuel feed line for any air leaks.



I'm also going to take my infrared heat gun and measure the exhaust runner temps for each cylinder and see if there's any difference.



I also have a spare crank sensor (as well as spare pressure relief valve, map sensor, ) that I will try just in case. The tech did say that sometimes the sensor can develop "flat spots" that do not generate codes, but can cause certain driveability issues.



Maybe in the end it could be the CP3, who knows! I just do not want to spend that kind of money yet until I go through the other things first.



Other than the above it was a fairly uneventful day!

 

[rbattelle]

Wow. Don't you just love these problems that seem to be complete magic?



Keep at it, I'm following this with great interest.



-Ryan

 

[JStieger]

I forgot to mention that Matt400 pm'ed me and mentioned that maybe the APPS (TPS) could cause this problem since this happens at a certain rpm. The tech also mentioned this, but again no codes to this effect.



The tech thinks that 1-2 injectors are just not firing properly at the low rpm. I looked in my Cummins HPCR book and it said that they need 90 volts to fire (DO NOT USE TEST LIGHT TO CHECK!) via capacitors in the ECM.



Later this afternoon I checked:



1) air in fuel by unplugging my line to my fuel pressure gauge isolator and opening the needle valve all the way. Result was clear as water. The tech said if there was air in this line that it would be noticeable like foaming/



2) replaced crank sensor with my "spare" to no effect. I don't know what surprises drivers more - black or light gray smoke?



3) measured exhaust runners 1" from block at idle and with engine fully warm and got:



#1 ~ 172*

#2 ~ 170*

#3 ~ 174*

#4 ~ 170*

#5 ~ 178*

#6 ~ 188*



I'm thinking #6 is hotter because of the coolant flow through the block (last cylinder and under cowl also so somewhat shielded from the open hood). Interestingly, the westach gauge from right above the turbo read 250*.



Tomorrow morning I'll pull the valve cover and check valve adjustment when cold as well as injector connections and hold-downs. I just want to check and rule out the "basics" before getting more complex.



BTW I asked about a cylinder contribution test and the tech said that was only available for later years since the DRB3 software for the 305/555 wasn't as developed.



That DRB3 tool is pretty neat - too bad it wasn't affordable for the public! It looked like one can take the freeze frame data from a code and try to have the truck run that data to see what happens. It also has a lab scope feature on it so that one can troubleshoot the cam and crank sensor where the crank sensor is supposed to have more square waves than the cam sensor by "X" amount. Looks like the waves go 0-5 volts peak-to-peak and have a set pattern if working correctly.

 

[rbattelle]

That DRB3 tool is pretty neat - too bad it wasn't affordable for the public!

I want one very badly. Maybe in 10 years they'll be as cheap as DRB-IIs are now.



Matt is a wise man, and his suggestion about the APPS made me think I remember reading somewhere in the 3rd gen boards about someone who had flat spots and it turned out to to be a problem with the APPS that didn't give any codes (now I can't find it). It is a hall-effect sensor, so it could easily have a problem in a specific position (1700 RPM). Did the tech with the DRB-III check out the signal from the APPS?



There might be a way to try this out for yourself. Will it stumble every time at 1700 RPM or so? If so, what about setting cruise control for like 1600 RPM, then using the "ACCEL" button to gradually accelerate up through 1700 RPM. Since your foot is off the throttle, the APPS signal is 0 and if the truck still stumbles then you know it's not the APPS causing a problem.



Not sure if this experiment is practical... can you engage cruise control in any gear? I've never tried it.



-Ryan

 

[JStieger]

I think I'll try the cruise suggestion. The tech didn't go through the APPS signal test, but I did notice yesterday that I couldn't set the cruise over 85 mph and then later in the day it worked at 88 mph...



First, though, I'm going to pull the valve cover while everything is cold.

 

[JStieger]

Update #...well I lost count...

Just got back from adjusting my valves. The job went a lot quicker after my neighbor saw me swearing and came over and loaned me his "Gear wrench" - it's basically a ratchet with a shallow socket with large opening so that an allen wrench can fit inside of it. This makes it really easy to set the valve lash and then tighten the locknut. Anyhow,



Before Adjust Intake / Exhaust:



#1 0. 010 / 0. 020

#2 0. 010 / 0. 023

#3 0. 012 / 0. 023

#4 0. 011 / 0. 023

#5 0. 012 / 0. 023

#6 0. 011 / 0. 023



After Adjust Intake / Exhaust:



#1 0. 010 / 0. 020

#2 0. 010 / 0. 020

#3 0. 010 / 0. 020

#4 0. 010 / 0. 020

#5 0. 010 / 0. 020

#6 0. 010 / 0. 020



I also checked my injector holdown bolts for proper torque. The service manual says 89 in-lbs, but I found they were all at ~55-60 in-lbs! So I torqued them down to ~75 in-lbs and stopped there since torque wrenches, small diameter fasteners, and I don't go well together... don't ask me how I know :{ (not on this truck!)



I also checked the wires to the injector for snugness and the wire nut torque and all were good.



Results:



1) Truck idles a lot smoother and quieter! It still has a bit of a lope, but less than before. The run up from idle to about 1800 rpms is kind of rough still though.

2) Driving the truck click/clacks and knocks less off idle. The "poof/sputtering/light grey smoke" is still reproducible on demand, but it seems like the duration of it is a bit shorter. I think I am on the right track by focussing on the injector system.

3) I tried Ryan's suggestion about the cruise control and it still did the poof/sputtering by just pressing the accel button only so it looks like the APPs is not the culprit.



Another tip about working over the engine - get a foam pad to stick over the hood latch - your belly and nether regions will thank you :-laf

 

[rbattelle]

JSteiger I wish you'd take pictures of this stuff!!



Glad you eliminated the APPS. Well, I should say I'm not glad you eliminated it... that would've been a cheap simple fix.



-Ryan

 

[JStieger]

JSteiger I wish you'd take pictures of this stuff!!



-Ryan

It dawned on me after I buttoned everything up, but I guess that I was too engrossed in what I was doing!



If I get up early enough tomorrow and feel energetic, I might go ahead and pull the valve cover again. I want to check the pushrods for straightness after I searched on here (or the other site) and a member had some of these types of issues and the dealer tech found a bent pushrod for whatever reason. In this case I have to pull all the rocker arms and redo everything, but it should go a lot quicker this time around... and I'll take pictures.



Off to WalMart to get some cheap ziploc bags to organize my parts tomorrow...

 

[JStieger]

just for Ryan - pictures!!

This morning I went and redid everything I did yesterday with the addition of checking the pushrods for straightness. This time I remembered to take pictures. I love inline engines! Super easy to work on and keep track of stuff. I also really appreciate DC for putting holes in the cowl so that you can lift the pushrods straight up and out for #5 and #6 cylinders. To adjust valves engine must be less than 140 F or preferably cold from sitting overnight.



First picture: valve train overview. The order from front to back is #1 intake, #1 exhaust, #2 intake, #2 exhaust, etc.



Second picture: close up of #1 intake and exhaust valvetrain. My pointer finger is next to the intake valves; my middle finger is next to the exhaust valves. In between is the injector with the wire nuts on top and the hold down bolts on each side.



Third picture: setting up damper to TDC. Service manual says 12 o'clock. Check if rocker arms on #1 and #2 are loose; if not this means that #6 is at TDC. No biggy though - if you want to start from the front like I do just rotate the damper another 360* until the TDC mark is at 12 o'clock again.



Fourth picture: adjusting the #1 intake valve lash with feeler gauge, 14 mm open end wrench for the locknut, and 5 mm allen wrench for the adjuster. I adjusted my intake to a tight 0. 010" and the exhaust to a tight 0. 020".



Fifth picture: removing the pushrod



Next post will have the rest of the pictures.

 

[JStieger]

rest of pictures

Sixth picture: checking pushrods for straightness by rolling on a flat surface with the cup hanging off the end. I also inspected the ends for cracking, pitting, wear. Every pushrod checked out OK.



Seventh picture: All the rocker assemblies from #1 removed leaving the crossheads and valve springs/keepers exposed.



Eighth picture: Checking the injector hold down torque with inch-lb torque wrench.

 

[rbattelle]

AWESOME! This thread will come in handy some day when I adjust my valves!



-Ryan

 

[JStieger]

Another thing is that the damper is marked TDC and the service manual states set to "12 o'clock" , but I couldn't find a 12 o'clock reference pointer for the TDC mark on the damper. So I just experimented with just left or right of my version of "12 o'clock", watched the rocker arms move, and the gap measurements were pretty consistent. I believe this is something to due with the cam movement relative to the crank movement and the lifters resting on a relatively "flat" spot on the cam lobe. Also, I do have a barring tool, but never used it as I couldn't find the access hole where I needed to put it. It seemed a heck of a lot easier to turn from where I did anyway - everything is right in front of you in clear view.



All in all it was about a 4 hour job taking my time. Next time around will probably be about 2 hours since it will be "old hat"!



Another tip to repeat: use a thick foam pad or pillow over the hood latch (or wear a jock strap! :-laf )

 

[rbattelle]

Look at those rocker arms... my goodness. They look cast to me. What a remarkable engine Cummins makes. This thing is built unbelieveably strong. No wonder they last forever. Ever see the 6. 0 rocker arms? I think they're just thick steel plates. Not sure about the Duramax (likely stamped).



Anyway, JSteiger, have you been reusing the valve cover gasket? I assume you have been... any leaks? Is it a rubberized type meant to be reused?



These threads of yours have made me want to crack open my valve cover and do the job just so I can say I conquered it.

 

[JStieger]

Anyway, JSteiger, have you been reusing the valve cover gasket? I assume you have been... any leaks? Is it a rubberized type meant to be reused?

The valve cover gasket is reusable - no leaks so far. The six bolts that hold down the valve cover have o-rings on them too for further sealing.